1. Technical Field of the Invention
This invention relates to electric motor-generators and, more particularly, to a high efficiency electro-mechanical energy conversion device which utilizes an unconventional configuration and unconventional operating parameters to achieve high efficiency operation.
2. Description of Related Art
Electric motors are known in which permanent magnets are mounted on a rotating shaft while electromagnetic armature coils on a stator are used to produce an armature magnetic field. Since the poles of the armature magnetic field are electromagnetically produced by an externally applied voltage source, the torque and speed resulting from the rotor response is a motor action. As the rotor turns, the magnetic flux lines of the permanent magnet rotor cut the turns of the armature windings wrapped on the stator. By Faraday's law, a voltage is induced in the armature turns, the magnitude of which equals the time rate of change of flux linkages (the derivative with respect to time of the product of the number of coil turns and the magnetic flux). In classical electric motors, this is a counter electromotive force (emf) or counter voltage which regulates the current flowing from the externally applied voltage or power source into the motor armature so that the actual torque produced by the armature equals only that amount needed to counteract the load torque and produce the desired speed of armature rotation.
The armature winding typically consists of a few turns of relatively thick wire in order to support the flow of large armature currents to develop the desired torque. Large armature currents are utilized because classical equations suggest that the rotor torque is directly proportional to the armature current. However, the requirement for large armature currents reduces the efficiency of the motor, with the efficiency being defined as the ratio of the rotational mechanical energy coming out of the motor to the electrical energy going in.
In order to overcome the disadvantages of existing electric motor-generators, it would be advantageous to have an Electro-Mechanical Energy Conversion (EMEC) device that greatly reduces the input current level required to achieve a desired output torque and the resultant output level of mechanical energy. The present invention provides such a device.